IMO, the Joker should be the one character that no one should be able to apprehend. He should be the one criminal that always eludes the Batman (thus giving Bats a reason to obsess over him) Sort of like those detectives that obsess over 20yr old cold cases where they know who did it, but because of a lack of evidence, can't put them away. Or, those detectives that try to track down serial killers but keep running into dead ends.

IMO, the only reason the Joker should ever be in Arkham, is because the Bat finally caught up with him and now he's facing the death penalty.

"Life ain't nothin' but bitches and money" - Ice Cube